Waste Dump/Stockpile Volumes
Rock mass can have three distinct states: Bank, Loose and Compacted:
- Bank rock is rock in its natural solid state (in-situ). The volume of bank rock (
) is measured in BCM (Bank Cubic Metres). - Loose rock is rock that is no longer in its natural state due to blasting and/or excavating. The volume of loose rock (
) is measured in LCM (Loose Cubic Metres). - Compacted rock is rock which were removed from its natural place and placed somewhere and then became compacted as effect of the gravity and tramming; the volume of compacted rock (
) is measured in CCM (Compacted Cubic Meters).
The volume of loose rock () is greater than the volume of bank rock () and the volume of compacted rock ().
The volume of compacted rock () is greater than the volume of bank rock ().
While this holds true for rock material, it is not always the case for some types of soil and sand, where the compacted volume is less than bank volume. Note however, that the weight of the material is always constant.
When we talk about waste dump volumes, we need to recognise that the volume of a designed waste dump is the volume of the material in its compacted state. Therefore, the volume of a waste dump wireframe (solid) is measured in Compacted Cubic Meters (CCM). From this, we can then calculate the loose or bank volume of the waste dump material. To convert between these measures of volume we need to apply a Swell factor (SF) and a Compaction Factor (CF).
To convert the bank volume to a loose volume, the following formula is used:
Or when SF is measured as a coefficient:
The Swell factor is always positive and is equal to or greater than 0%. It is measured as a percentage, for example 40%.
To convert the loose volume to a compacted volume, the following formula is used:
Or when CF is measured as a coefficient:
The Compaction factor is always positive and is equal to or greater than 0% and is less than 100%. It is measured as a percentage, for example 20%.
If it is omitted, then the Compaction factor is assumed to be equal to 0% by default. In this case, the loose volume and the compacted volume are the same.